Um... WTF is this bolt from?
 

Found in my driveway where i park the SD...

Alternator bolt? looking at the wear pattern.

I've seen wear like that on a drive shaft flange that had loosened up.

looks some kind of driveshaft bolt i was just taking out the other day on my 300d.. i know the w126s have those same bolts as well

That definitely looks like a guibo flange bolt. From the picture it looks like the threads were stripped, is that the case?

looks very much like the viscous fan center bolt, again it could have been stripped if not fully tight.

Looks like a flex disk bolt to me.


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We have a winner...

Now i need a front section driveshaft for my 82SD...

Im replacing the flex disc and bolts for now... but it wont last long.

Hey, keep that filthy word on the BMW forums! :freak:

-Rog

@Vtech: Why are you installing a used flex disk? It is enough of a pita to do the job once. Why do you need a front drive shaft? All of the parts to repair are still available.

For what it's worth, when this happened to me, the flange on the output shaft of transmission wore along with the bolt. The hole elongated and enlarged a fair amount. I talked it over with a friend of mine who had worked as an engineer, inventor, engine builder, mechanic and garage owner.

'New nut and bolt, and make them tight'

This is because a properly torqued non interference joint is effective because of the friction at the clamped faces, and not by interaction of the fastener with the bores of the respective holes.

I looked for a while for a new output flange but moved on to other things. This fix outlasted the original motor and body of the 240D, probably 10-20k miles.

Seen before on PP.

http://www.peachparts.com/shopforum/diesel-discussion/295914-driveline-uh-oh.html

Sorry
 

'Don't need that kind of interference.

I have a good driveshaft from a 380 SE and both the transmission and differential yokes if you get stuck. The flex disk are a bit bigger than those on the SD but the driveshaft is a bit smaller in diameter. No charge if you can use it.

I wonder if a yoke could be repaired by a machinist. I know they can weld crankshafts and turn them to the original diameter. I wonder if this would be a good repair on a yoke with an oblong hole?

While you're dealing with this will you look and see if there's a spacer plate between the rear engine mount and the cross member?

I remember one falling out but I can't remember if it fell out when I was tearing down the 380SE or the 300SD. It seems like it was about 1/4" thick but I can't find the dang thing now. I may have to make one if I need it.

Thanks, holler if you can use the shaft.